Conduct a longitudinal study of biologic markers in breast cancer patients. Evaluate tissue and serum markers currently proposed as being potentially useful and will develop a new set of markers from placental membrane proteins and glycoproteins and investigate their presence in serum and tissue. These studies will be coordinated with a well defined clinical study of breast cancer sponsored by the Northern California Cancer Program and conducted by the Northern California Oncology Group. This will provide a set of patients whose clinical care will be rigorously controlled and will also be to ensure direct control of specimens and accurate patient information. There will be twelve major institutions participating in these studies. The NCOG protocols will evaluate the patients by routine tests, and these will be complemented by our evaluation of the markers that will be measured in this protocol.